From Icacina guesfeldtii (leaves and roots), two new diterpene-based alkaloids have been isolated and identified as icaceine (2) and De-N-methylicaceine (3). Icacine (1) occurred both in the leaves and roots. Structure determination was performed by spectroscopic and chemical methods. As icacine (1), these two bases are the first alkaloids with a pimarane skeleton isolated from plants. © 1980.